The present invention relates to fluid control apparatus comprising a regulator such as a massflow controller for controlling the rate of flow or a pressure regulator for regulating pressure, an on-off valve, etc. in combination.
Fluid control apparatus are known which comprise a regulator for regulating the rate of flow or pressure, a regulatlor extension provided on each of the front and rear sides of lower end or the regulator, and a connecting member butted against the bottom face of the extension, the extension being removably connected to the connecting member with a seal portion interposed there-between so that an inverted L-shaped channel formed in the extension and having an opening in its bottom face communicates with an L-shaped channel formed in the connecting member and having an opening in its upper surface (see JP-A-241400/1994).
With the fluid control apparatus of the type described, it is necessary to frequently perform the procedure of removing the regulator and installing the regulator again for the maintenance and inspection of the regulator. Accordingly, it is desired to mount the fluid control apparatus on an aluminum panel so as to render the regulator singly removable upward. With the conventional fluid control apparatus described, therefore, the regulator is attached to the connecting member by inserting two bolts through the regulator extension and screwing the bolts into respective threaded bores in the connecting member.
With the conventional apparatus, the two bolts are positioned symmetrically on opposite sides of the seal portion. To ensure fluid tightness by the seal portion, there is a need to alternately tighten the two bolts by a small amount each time with consideration given to the balance between the bolts. Thus the apparatus has the problem that this procedure is cumbersome and difficult. Further in the case where the panel for mounting the apparatus thereon is vertical, difficulty is experienced in screwing the bolts into the respective threaded bores in the connecting member, so that the apparatus also has the problem of causing damage to the seal portion by this procedure to result in impaired fluid tightness, and the problem of allowing the bolt to fall off and become lost in removing the regulator.
When the regulator is a massflow controller, the flow rate is controlled on the premise that the fluid flowing into the controller is in the form of a laminar flow, whereas turbulence will occur because the fluid passes through the inverted L-shaped channel and the L-shaped channel before flowing into the massflow controller. This entails the problem of impairing the flow rate control accuracy of the controller.